A reciprocating piston compressor of the above kind is disclosed in German patent 199 03 025. The reciprocating piston compressor disclosed in this patent is for a gaseous medium and includes a piston movable within a cylinder. An end of the piston lies outside of the cylinder and is connected to the drive shaft of an electric motor. The reciprocating piston compressor and the drive unit are mounted in a compressor housing and a drive unit housing. A tubularly-shaped projection piece configured as one piece with the compressor housing is arranged on the compressor housing in the region of the piston. The compressor housing and the drive unit housing are configured as one piece. The reciprocating piston compressor known from this patent is configured in the conventional manner and has the disadvantage of needing substantial space for mounting and has the further disadvantage that there is high friction of the piston ring on the cylinder running path especially during the intake stroke.
A reciprocating piston compressor is also known from German patent 100 05 929 which drives a piston machine via a drive motor. A work chamber of the cylinder has a volume which pulsates between a smallest and a largest value. Inlet and outlet openings are provided with inlet and outlet elements, respectively. A medium is pushed through via the inlet and pushed out via the outlet with the inlet and outlet openings being separate. A crankshaft space is surrounded by a crankcase housing and is connected upstream of the work chamber of the cylinder. The crankshaft space is connected to the ambient via an intake support closeable by means of an air inlet valve. The air inlet valve is a rotation valve and is controllable in synchronism to the rotational movement of the crankshaft. An intake filter is integrated into the intake support and is connected ahead of the rotation valve. The intake support, the intake filter and the rotation valve form a single component. The reciprocating piston compressor known from German patent 100 05 929, which is configured in the conventional manner, also has the disadvantage of having a large construction and high friction of the piston ring on the cylinder running path especially during the intake stroke.